A Simple Technique for the Prediction of Interacting Proteins Reveals a Direct Brn-3a-Androgen Receptor Interaction

Abstract

The formation of multiprotein complexes constitutes a key step in determining the function of any translated gene product. Thus, the elucidation of interacting partners for a protein of interest is of fundamental importance to cell biology. Here we describe a simple methodology for the prediction of novel interactors. We have applied this to the developmental transcription factor Brn-3a to predict and verify a novel interaction between Brn-3a and the androgen receptor (AR). We demonstrate that these transcription factors form complexes within the nucleus of ND7 neuroblastoma cells, while in vitro pull-down assays show direct association. As a functional consequence of the Brn3a-AR interaction, the factors bind cooperatively to multiple elements within the promoter of the voltage-gated sodium channel, Nav1.7, leading to a synergistic increase in its expression. Thus, these data define AR as a direct Brn-3a interactor and verify a simple interacting protein prediction methodology that is likely to be useful for many other proteins.Although the importance of protein-protein interaction is long established, the rise of postgenomic technologies, in particular interactomics in yeast (1), and the growing popularity of systems biology (2) have served to highlight the importance of protein complexes to cell biology. For example, in the field of transcriptional regulation, the discovery of cis-regulatory elements vast distances from the transcriptional start site of a gene requires the formation of protein complexes to bridge often huge expanses of genomic DNA (3). In addition, the concept of promoters and cis-regulatory elements as "coincidence detectors" that integrate and process a diversity of inputs into a decision on the expression of a gene requires the construction of complex molecular machinery to perform these tasks (4). Although the need to study multiprotein complexes in basic research is clear, its relevance to applied disciplines should not be underestimated. In the case of transcriptional complexes, there is a growing body of data supporting the idea that interactions between transcription factors and between transcription factors and co-factors constitute a potent target for therapeutic intervention (5-7). In addition to molecules that block or disrupt protein-protein interactions, the creation of drugs that stabilize a transcriptional complex has been postulated (6), thus suggesting the possibility that, by modulating protein binding events, genes critical to pathological processes may be switched on or off pharmacologically.The Brn-3a transcription factor (also known as Pou4F1) is a class IV POU (Pit-Oct-Unc) family transcription factor. It is expressed at high levels in the sensory neurons of the trigeminal ganglia and dorsal root ganglia (DRG) 2 and in specific structures of the brain (8). Brn-3a is indispensable for normal development because Brn-3a knock-out mice display a severe depletion of sensory neurons. Presumably grossly impaired in nociception and proprioception, these animals are unable to...

The lncRNA SLNCR1 Mediates Melanoma Invasion through a Conserved SRA1-like Region

“…Third, other AR-associated lncRNAs have been shown to induce AR in a ligand-independent manner (Yang et al, 2013; Zhang et al, 2015). Fourth, AR forms functional heterodimers with other TFs, and was previously shown to directly bind Brn3a in mouse ND7 cells (Berwick et al, 2010; Chen et al, 1997; Lee et al, 1999). These data are consistent with formation of a heterodimer TF complex which significantly increases TF affinity for the tandem TFBSs than either TF alone.…”

EMT, stemness and tumor plasticity in aggressive variant neuroendocrine prostate cancers

“…In patients, high Brn2 expression is a characteristic of NEPC and is correlated with low serum PSA levels [46]. Interestingly, AR has also been shown to interact directly with a related neuronal transcription factor Brn3a (a player known for its anti-apoptotic functions) to promote the expression of the Nav1.7 voltage-gated sodium channel SCN9A, which is correlated with tumor progression [47–49]. However, AR directly repressed the expression of the NEPC self-renewal marker Sox2, and inhibiting AR activity via enzalutamide treatment robustly upregulated Sox2 expression in multiple prostate cancer cell lines [50].…”

TRANSCRIPTION FACTOR BRN-3α AND PROSTATE CANCER, RELATION WITH HORMONE RECEPTORS AND AKT/M-TOR SIGNALING PATHWAY ACTIVATION

“…Это свиде-тельствует о том, что в трансформированных клет-ках простаты происходит увеличение экспрессии данного маркера, что влияет на уровень рецепторов стероидных гормонов. Этот факт подтверждается также экспериментальными данными, полученны-ми D.C. Berwick et al [2]. Авторами доказано влия-ние данного показателя на рост транскрипционной активности рецепторов ER и AR.…”

“…Они представляют собой важные ядерные белки, регулирующие процессы пролиферации и дифференцировки клетки. Полага-ют, что транскрипционный фактор Brn-3α вовлечен в различные процессы онкогенеза, в частности, участвуя в проведении апоптотических сигналов и контролируя скорость клеточного цикла [2]. Кроме того, определено влияние данного показателя на уровень экспрессии рецепторов половых гормонов: эстрогенов (ER) и андрогенов (AR) [3].…”